On the surface is may appear that there are similarities between these European CDs which pair an eclectic guitarist with an academically trained electronics manipulator for extended improvisations. But while both have much to offer the adventurous listener, they couldn’t be more unlike.

For a start, Rebetika is involved with the rearrangement, reassembling and deconstruction of nine rebetika tunes, using samples of the early 20th century so-called Greek blues as the base on which to perform electronically altered, re-compositions. Falter 1-5, on the other hand, deals with abstraction and pure sound, treating the reconstituted sonic properties of the one “real” instrument – the guitar – as a sound source no different from those created by objects such as a mixing-board, tapes and analogue electronics.

On the other hand, because the recorded material with which Yannis Kyriakides and Andy Moor work includes vocals by songsters with the aggressive timbres of Country Blues singers such as Son House and Charley Patton, the tracks are suffused with emotion. In contrast, Ernst Karel’s and Annette Krebs’ five improvisations are precise and clinical, only divorced from microtonal parameters at those junctures when triggered samples clash with simultaneously outlined electronic pulses.

Perhaps that’s to be expected. Cyprus-born, London-raised, Amsterdam-based Kyriakides teaches composition at The Hague’s Royal Conservatory of Music, is artistic director of Ensemble MAE and has composed in a wide variety of media. Concerned with traditional performance practices, digital media and sensory space, he has improvised with players such as London saxophonist John Butcher. Even more visceral in his creations, British guitarist Moor has been a mainstay of Dutch Punk-Improvisers the Ex since 1990, works with French sound poet Anne James Chaton, creates film soundtracks and improvises with the likes of drummer Han Bennink.

Classically trained, Berlin-based guitarist Krebs is more interested in reductionist sounds and their relation to the sonic impulses from objects and electronics. Over the years she has improvised with trumpeter Axel Dörner and harpist Rhodri Davies among others. Manager of Harvard University’s Sensory Ethnography Lab and the Film Study Center, Karel has researched the anthropology of sound; recorded, mixed and sound designed himself; has mastered and re-mastered CDs; as well as improvised on trumpet and/or analog electronics, most notably in the EKG duo with oboist Kyle Bruckmann.

Animated with chunky granular synthesis, radio-tuning static and undifferentiated drones, Falter’s five tracks are punctuated with samples of captured broadcast sounds –and silences. A definitive guitar lick appears on track one, but isn’t replicated anywhere for the remainder of the disc. Instead a contrapuntal intermix of impulses from both sources precede fortissimo explosions which seem to consist of scrubbed friction, shaking wave forms and samples of remote mumbling voices These tones slowly unroll until the staccato impulses are superseded by envelopes of abstracted ring modulator-like whooshes and clawing abrasions.

Layered and spiraling, the mercurial drones and mechanized sideband pulsations, cascade throughout before reaching a crescendo of intermingled pops, thumps and ruffled extensions during the 20 minutes of “Falter 5”. Grinding and inconsistently balanced flanges buzz motor-like and are mixed with split-second voice samples that squeal, burp and resonate as their properties are mixed down alongside snatches of music and synthesized, granular intermittent yelps and buzzes. Following a vigorous intermezzo that exposes refractive whistles, pressurized machine-gun-like fire and signal-processed sound leaks, plus additional novel tones that could come from a jackhammer or recording tape running off a reel, these timbres are finally superseded by strident, inchoate drones that in this context appear positively relaxing. Before a fade, the timbres resulting from each improviser’s strategy begin to mirror one another.

Crackles, buzzing and granular pulses also emanate from Rebetika’s nine tracks, but whether some of the dirty glitches result from processing or have been ground into the surface of 78 rpm discs during the past century remains moot. What Moor and Kyriakides do is to match the extended Country Blues-like growl of the original performers with oscillating references from a laptop plus Moor’s percussive strumming and near bottleneck styling.

Sharply picking his guitar strings, Moor’s vibrating chord structures mirror the original performances in intensity, with his snaps and runs toughened by Kyriakides’ vibrating chordal pulsations. Examples of this appear on “Haremi” and “A School Burnt Down”. On then later, Moor’s straight-ahead flat picking is only audible in snatches as the backing oscillations almost subsume guitar licks. Cutting through the computer program’s time-stretching, the guitarist eventually reappears with a broken chord reprise. As for “Haremi”, an aleatoric overlay of wiggling whistles, ramping pops and repeated grooves from Kyriakides finally manage to connect with Moor’s neck tapping and downward string splintering. This pulsing interface adds lyrical depth both to Moor’s playing and the original melody.

Then on “Five in Hell”, the two manage to mix ganularized software samples with the acoustically-recorded 78, in such a fashion that not only does the weight of the elderly needle create its own percussion line, but the distorted and refracted fiddle and guitar samples are also accompanied by accelerated pulses from the computer. Moor’s bass string thumps help the laptop pulsations create a pedal-point base for the initially recorded sounds, with the distinctive tune’s coda an unprocessed, old-time fiddle solo.

Using traditional and newly invented instruments and processes, both international duos have created distinctively novel electro-acoustic melding, neither of which owes anything to the others’ strategies. Preference for stark abstraction or melody glimmers will influence whether listeners appreciate one more than the other.